Polyamide

Abstract

A polyamide characterized in that the polyamide is obtained by thermal polycondensation of (a) dicarboxylic acid components comprising 10 to 80% by mole in total carboxylic acid components of 1,4-cyclohexanedicarboxylic acid having a trans / cis molar ratio of 50 / 50 to 97 / 3 and (b) an aliphatic diamine component is disclosed. The alicyclic polyamide having 1,4-cyclohexanedicarboxylic acid in a backbone thereof as a dicarboxylic acid unit, which is suitable as materials for various uses such as automotive parts, electric / electronics parts, industrial materials, engineering materials and daily household goods, and superior in heat resistance, low water absorption, light resistance, moldability and light weight, as well as superior in toughness, chemical resistance and appearance, and molded articles thereof.

Description

[0001] The present invention relates to a new polyamide and molded articles thereof. In more detail, the present invention relates to a new polyamide superior in moldability, heat resistance, light resistance and weather resistance, as well as superior in toughness, low water absorption, chemical resistance and appearance. The inventive polyamide is also suitable as materials for various uses such as automotive parts, electric / electronics parts, industrial materials, engineering materials and daily household goods, and molded articles thereof.PRIOR ART[0002] Polyamides, represented by nylon 6 and nylon 66, have been widely used as materials for various uses such as clothing, industrial materials, automotive parts, electric / electronics parts and engineering parts, due to superior moldability, mechanical properties and chemical resistance.[0003] However, with the recent demand for weight reduction of parts, a substitute for metals used in the parts is molded polyamide. As such, the me...

AI Technical Summary

Benefits of technology

[0009] The present inventors, after an extensive study to solve the above-described problems, found that the problems described above were able to be solved by a new alicyclic polyamide obtained by polycondensation of dicarboxylic acid components containing 1,4-cyclohexanedicarboxylic acid having a specified trans / cis molar ratio and a diamine component. In particular, the present inventors found that a semi-alicyclic polyamide, which was a copolymerized polyamide of said alicyclic polyamide with other types of nylon, was able to effect remarkable improvements, and thus accomplished the present invention.

Problems solved by technology

More specifically, conventional nylon 6 and nylon 66 are not satisfactory in heat resistance, dimensional stability, mechanical properties and chemical resistance and thus cannot be used at present, for example, in an electric / electronics application where a heat resistance for reflow soldering is required along with a development of surface mounting technology (SMT), or an application for under-hood automotive parts where the requirements have been raised year after year.

However, although PA46 has good moldability and heat resistance, it has problems of remarkably large dimensional change and lowering in mechanical properties caused by water absorption.

A polyamide composed of terephthalic acid and 1,6-hexanediamine (which may be abbreviated as PA6T type hereinafter) also has a such high melting point as about 370.degree. C., but it is difficult to obtain molded articles with satisfactory properties by melt molding due to vigorous thermal degradation of the polymer itself.

Said 6T type copolyamide really has low water absorption, high heat resistance and high chemical resistance, but has disadvantages such as inferior moldabilty, toughness and light resistance.

Said copolyamide also has a high specific gravity, resulting in a problem in weight reduction.